Various power converters are known in the art and used in many applications currently in the marketplace. A generalized example of one type of power converter is the conventional buck converter 100 of FIG. 1. The buck converter 100 is a Direct Current (DC)-DC converter, such as may be used to decrease the voltage from a battery and supply a DC voltage to an electronic component.
The buck converter 100 includes transistors 102, 104 that are controlled by a control circuit 106. The buck converter also includes a diode 108, a capacitor 112, and an inductor 110. A load 120 receives the output voltage of the buck converter 100. The control circuit 106 varies the duty cycles at which the transistors 102, 104 are turned on to alternately connect and disconnect the inductor 110 with the source voltage (Vin). As the inductor 110 stores energy and discharges the energy, it produces the output voltage (Vout), which is somewhat smaller than the source voltage.
Another example of a conventional power converter is shown in FIG. 2. The power converter 200 includes switches 210, 220, which complete paths to two separate capacitors 211, 221. The power converter 200 produces two output voltages (Vout1 and Vout2) and supplies two different loads 212, 222. In some implementations, the output voltages are different.
Such power converters find use in a wide assortment of consumer devices, such as cellular phones and laptop computers. An example use of a DC-DC power converter is to reduce a voltage from a battery to a voltage for use in a processor device. A fast transient response is desirable in order to keep up with the moment-to-moment power consumption of a high performance processor core. Furthermore, a fast transient response may help to provide fast settling efficiently when fast dynamic voltage scaling is employed. Thus, it is desirable to use very high frequencies in a DC-DC converter that is paired with a digital core. It is also desirable to limit the size of passive components so they can be placed close to the load.
However, when a direct conversion from battery voltage is employed, the necessary voltage rating of the Metal Oxide Semiconductor (MOS) transistors may force the use of transistors that are very lossy at high frequency. On the other hand, operation at low frequency involves the use of bulky inductors and capacitors, which take up large amounts of board space, especially when multiple voltage domains are used.